Universal power control device

ABSTRACT

The present invention is directed to an intelligent dimmer that is capable of “learning” the type of load it is controlling, and adjusts its operating parameters accordingly. The present invention can adaptively drive electrical loads over a wide range of wattages. The intelligent dimmer of the present invention is configured to automatically calibrate itself based on the load current demands of a particular electrical load. The intelligent dimmer of the present invention also adaptively limits in-rush currents to extend the life expectancy of the solid state switching components used therein.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.13/792,566, filed on Mar. 11, 2013, the content of which is relied uponand incorporated herein by reference in its entirety, and the benefit ofpriority under 35 U.S.C. §120 is hereby claimed; this application alsoclaims priority to U.S. Provisional Patent Application Ser. No.61/635,600 filed on Apr. 19, 2012, the content of which is relied uponand incorporated herein by reference in its entirety, and the benefit ofpriority under 35 U.S.C. §119(e) is hereby claimed.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates generally to electrical wiring devices,and particularly to power control wiring devices such as dimmer and fanspeed control devices.

2. Technical Background

In most residences, a simple ON/OFF switch may be the primary way peoplecontrol the home's lighting fixtures or air-circulating fan fixtures.One obvious drawback to using simple ON/OFF switches to control thesedevices is experienced by the homeowner when he pays the electricalbill—a given light (or fan) is either ON or OFF—a simple switch is thusunable to vary the amount of light (and hence control the amount ofpower consumed). Stated differently, by controlling light intensity orfan speed in accordance with needed or desired parameters, electricityusage is reduced, saving money and natural resources. In accordance withthe present invention, therefore, a power control device refers to anelectrical control device that may be employed to adjust the amount ofcurrent delivered to any variable electrical load, such as a light or amotor.

When the electric load is a lighting device, the power control device iscommonly referred to as a dimmer. For example, when a light is dimmed25% by a dimmer, a 20% reduction in the amount of electricity requiredto operate the lamp is realized. When a light is dimmed by 50%, a 40%electricity reduction is realized. Second, a dimmer greatly extends lamplife because it reduces the strain on the filament. When a light isdimmed 25%, a given lamp lasts four (4) times longer than it would atfull power. When the light is dimmed by 50%, it can last as much as 20times longer (than a light that is continuously operated at full power).If the power control device is configured to control a motor, such as afan motor, the power control device is referred to as a motor speedcontroller. Motor speed controllers are also used to control the speedof machinery such as power tools, electric drills, chair lifts,stationary machinery, and other such variable speed motor drivenelements.

Power control devices are typically packaged in a wiring device formfactor for installation in a wall outlet box. The wiring device mayinclude one or more power control devices within the device housing. Forexample, wiring devices that are equipped with both fan motor controland lighting control features are ubiquitous. The exterior of the wiringdevice includes either screw terminals or wire terminals for subsequentconnection between the AC power source and the load. The conventionalwiring device form factor also provides a user accessible interface thatincludes one or more switch mechanisms such as buttons, levers, dials,slide switches, and other such input control mechanisms that permit auser to vary the power to a load or turn it ON/OFF.

Prior to device installation, wiring from the AC power source and wiringto the load(s) are disposed inside the outlet box. The outlet box isusually located proximate to the load being controlled. The device isinstalled by connecting the wiring inside the outlet box to theappropriate wiring device terminals disposed on the exterior of thewiring device. The power control wiring device is then inserted into theoutlet box and attached to the outlet box using one or more fasteners. Acover plate is installed to complete the installation. One of thedrawbacks associated with older conventional power control devicesrelates to the fact that many of these devices were often installedwithout a neutral wire being routed into the device box. What is neededtherefore is a power control device that can be employed in anystructure being retrofitted or remodeled. Stated differently, a powercontrol device is needed that can work with existing wiringconfigurations (whether the device box includes a neutral wire or doesnot include a neutral wire).

Often, a residence includes a three way lighting arrangement whereby onelight fixture may be operated by two separate three-way switches. Often,one three-way switch is installed at an upstream location while a secondthree-way switch is installed at a downstream location. This allows aresident to conveniently turn the lights ON or OFF from two differentlocations. Unfortunately, this may lead to difficulties when a structureor space is being retrofitted, since certain conventional dimmers mayonly be installed at one of the three way switch locations. Thisrequires the homeowner to know how the existing wiring is disposed inthe room (behind the plaster or sheet rock). What is needed therefore isa dimmer that can be installed at any of the three-way switch locations.

Turning now to so-called “green” issues, the public has developed anincreased awareness of the impact that energy generation has on theenvironment. Moreover, as the economies of countries such as Brazil,India, China, etc. improve and develop their need for energy resourcesincreases accordingly. As such, the global demand for energy has risensharply, while the supply of planet earth's resources remains fixed. Inlight of the pressures of supply and demand, the cost of energyresources will only increase. There is thus a need to use limited energyresources more wisely and more efficiently. More efficient light sourcesand electrical fixtures have been developed to replace the conventionalincandescent lighting devices in response to this need. For example,compact fluorescent lights (CFL) and light emitting diode (LED) devicesare far more efficient than conventional incandescent lights and thusprovide homeowners/tenants with an acceptable level of service whileusing less energy and incurring lower costs.

One of the drawbacks of conventional dimmer devices relates to the factthat incandescent lights, fluorescent lights, MLV lighting, ELVlighting, CFL devices and LED lighting may have different electricaloperating characteristics. Dimmers have a solid state switchingcomponent that turns the lamp on during a user adjustable portion ofeach line frequency cycle and turns the lamp off during the remainingportion of the cycle. Dimmers that turn the load ON at a zero crossingof the line frequency and OFF at a subsequent phase angle are referredto as “reverse phase” dimmers. Dimmers that turn the load ON at selectedphase angle and turn the load OFF at the following zero cross are knownas “forward phase” dimmers. Each type of load will be less susceptibleto unwanted effects (such as flickering) when it is properly matched toan appropriate dimmer. Moreover, the life expectancy of the both thedimmer and the load may be adversely affected if the dimmer and the loadare not properly matched. When a user installs a light source (load)that is not matched to the corresponding dimmer, the light will notoperate properly and the user will either have to change the lightsource or the dimmer to rectify the situation.

Accordingly, a need exists for a power control device that can driveelectrical loads over a wide range of wattages. A need also exists foran intelligent dimmer that is capable of recognizing the type of load itis driving, and adjust the drive signal to match the operatingparameters of the load. For example, an intelligent dimmer is neededthat can automatically calibrate the dimmer based on the load currentdemands of a particular electrical load. The intelligent dimmer shouldalso be able to adaptively limit in-rush currents that are known toshorten the life expectancy of the solid state switching components usedin dimmer products.

SUMMARY OF THE INVENTION

The present invention addresses the needs described above by providingan intelligent dimmer that can be employed in any structure beingretrofitted or remodeled. The present invention may be installed inexisting wiring, i.e., whether the neutral is present or not present inthe device box. The intelligent dimmer of the present invention may alsobe installed at either three-way switch location in a retrofit withoutregard to how the electrical wiring is disposed in the existingstructure. The present invention is directed to an intelligent dimmerthat is capable of recognizing the type of load it is controlling, andadjust the drive signal to match the operating parameters of the load.The present invention can adaptively drive electrical loads over a widerange of wattages. The intelligent dimmer of the present invention isconfigured to automatically calibrate itself based on the load currentdemands of a particular electrical load. The intelligent dimmer of thepresent invention also adaptively limits in-rush currents to extend thelife expectancy of the solid state switching components used therein.

One aspect of the present invention is an electrical wiring device thatincludes a housing assembly having a plurality of terminals at leastpartially disposed therein, the plurality of terminals being configuredto be coupled to an AC power source and at least one electrical load. Asensor element is coupled to the plurality of terminals and configuredto provide a sensor signal based on at least one load power parameter ofthe at least one electrical load. At least one variable controlmechanism is coupled to the housing assembly, the at least one variablecontrol mechanism being configured to adjustably select a useradjustable load setting, the user adjustable load setting beingadjustable between a minimum setting and a maximum setting. At least oneseries pass element is coupled between the AC power source and at leastone electrical load, the at least one series pass element beingconfigured to provide output power to the at least one electrical loadin accordance with the user load setting, the output power being lessthan or equal to the AC power. A regulation circuit is coupled to thesensor element and the at least one series pass element, the regulationcircuit being configured to enter a calibration mode when AC power isapplied to at least a portion of the plurality of terminals, in thecalibration mode the regulation circuit being configured to provide theat least one series pass element with an initial output power settingwhile monitoring the at least one load power parameter, the regulationcircuit being further configured to increment the initial output powersetting to at least one incremental output power setting whilemonitoring the at least one load power parameter, the regulation circuitbeing configured to identify a load type of the at least one electricalload based on the at least one incremental output power setting and theat least one load power parameter that results in the at least oneelectrical load being energized, the regulation circuit selectingcalibration values based on the load type, the selected calibrationvalues corresponding to the minimum setting and the maximum setting.

In one embodiment, the plurality of terminals includes a neutralterminal or a ground terminal.

In one embodiment, the identified load type determines if the at leastone electrical load operates in a forward phase control mode or areverse phase control mode.

In one embodiment, the regulation circuit includes a microcontrollercoupled to a memory, the memory being configured to store a plurality ofcharacteristic load curves stored therein, the plurality ofcharacteristic load curves including a plurality of incremental powersettings and a plurality of load power parameters, each characteristicload curve of the plurality of characteristic load curves correlatingeach load type with a predetermined incremental output power settingversus a predetermined load power parameter.

In one version of the embodiment, the predetermined load power parameterincludes an inrush current parameter.

In one embodiment, a power supply coupled to the AC power source, thepower supply being configured to provide at least one supply voltage.

In one version of the embodiment, the power supply is a half wave powersupply that is selectively coupled to the AC power source via one ofthree diodes, and wherein the plurality of terminals includes a phaseterminal, a first traveler terminal and a second traveler terminal, thepower supply being individually coupled to phase terminal, a firsttraveler terminal and a second traveler terminal by corresponding diodesof the three diodes.

In one embodiment, the regulation circuit includes a zero cross circuitcoupled to the AC power source via one of three electrical paths, eachof the three electrical paths including a diode.

In one version of the embodiment, each of the three electrical paths arecoupled to one of a first traveler terminal, a second traveler terminalor a phase terminal.

In one embodiment, the regulation circuit is configured to enter thecalibration mode when at least a portion of the at least one variablecontrol mechanism is actuated.

In one version of the embodiment, the portion includes an ON/OFFcontrol.

In one embodiment, the sensor element is a current sensor configured tosense current propagating through the at least one electrical load.

In one embodiment, the at least one electrical load is selected from agroup of electrical loads including a variable speed motor, anincandescent lighting load, a magnetic low voltage (MLV) load, afluorescent lighting load, an electronic ballast (EFL) type lightingload, a halogen light load, an electronic low voltage (ELV) load, and acompact florescent light (CFL) load.

In one embodiment, the series pass element is selected from a group ofseries pass elements including a thyristor device, a triac device, andat least one transistor device.

In one version of the embodiment, the at least one transistor deviceincludes a first MOSFET transistor coupled to a second MOSFETtransistor, the first MOSFET transistor being configured to provide theoutput power in a first half cycle of the AC power source and the secondMOSFET transistor being configured to provide the output power in asecond half cycle of the AC power source.

In another aspect, the present invention includes an electrical wiringdevice that includes a housing assembly having a plurality of terminalsat least partially disposed therein, the plurality of terminals beingconfigured to be coupled to an AC power source and at least oneelectrical load. A sensor element is coupled to the plurality ofterminals and configured to provide a sensor signal based on at leastone load power parameter of the at least one electrical load. At leastone variable control mechanism is coupled to the housing assembly, theat least one variable control mechanism being configured to adjustablyselect a user adjustable load setting, the user adjustable load settingbeing adjustable between a minimum setting and a maximum setting. Atleast one series pass element is coupled between the AC power source andat least one electrical load, the at least one series pass element beingconfigured to provide output power to the at least one electrical loadin accordance with the user load setting, the output power being lessthan or equal to the AC power. A regulation circuit is coupled to thesensor element and the at least one series pass element, the regulationcircuit being configured to enter a calibration mode when AC power isapplied to at least a portion of the plurality of terminals. In thecalibration mode the regulation circuit is configured to provide the atleast one series pass element with an initial output power setting whilemonitoring the at least one load power parameter, the regulation circuitbeing further configured to increment the initial output power settingto at least one incremental output power setting while monitoring the atleast one load power parameter, the regulation circuit being configuredto select a forward phase control mode or a reverse phase control modebased on the at least one incremental output power setting or the atleast one load power parameter that results in the at least oneelectrical load being energized.

In one embodiment, the regulation circuit selects calibration valuesbased on which of the forward phase control mode or the reverse phasecontrol mode is selected, the selected calibration values correspondingto the minimum setting and the maximum setting.

In one embodiment, the regulation circuit is configured to identify aload type of the at least one electrical load based on the at least oneincremental output power setting and the at least one load powerparameter that results in the at least one electrical load beingenergized, the regulation circuit selecting calibration values based onthe load type, the selected calibration values corresponding to theminimum setting and the maximum setting.

In one embodiment, the plurality of terminals includes a neutralterminal or a ground terminal.

In one embodiment, the regulation circuit includes a microcontrollercoupled to a memory, the memory being configured to store a plurality ofcharacteristic load curves stored therein, the plurality ofcharacteristic load curves including a plurality of incremental powersettings and a plurality of load power parameters, each characteristicload curve of the plurality of characteristic load curves correlatingeach load type with a predetermined incremental output power settingversus a predetermined load power parameter.

In one embodiment, a power supply is coupled to the AC power source, thepower supply being configured to provide at least one supply voltage.

In one version of the embodiment, the power supply is a half wave powersupply that is selectively coupled to the AC power source via one ofthree diodes, and wherein the plurality of terminals includes a phaseterminal, a first traveler terminal and a second traveler terminal, thepower supply being individually coupled to phase terminal, a firsttraveler terminal and a second traveler terminal by corresponding diodesof the three diodes.

In one embodiment, the regulation circuit includes a zero cross circuitcoupled to the AC power source via one of three electrical paths, eachof the three electrical paths are selectively coupled to one of a firsttraveler terminal, a second traveler terminal or a phase terminal via adiode.

In one embodiment, the regulation circuit is configured to enter thecalibration mode when at least a portion of the at least one variablecontrol mechanism is actuated, the portion including an ON/OFF control.

In one embodiment, the sensor element is a current sensor configured tosense current propagating through the at least one electrical load.

In one embodiment, the at least one electrical load is selected from agroup of electrical loads including a variable speed motor, anincandescent lighting load, a magnetic low voltage (MLV) load, afluorescent lighting load, an electronic ballast (EFL) type lightingload, a halogen light load, an electronic low voltage (ELV) load, and acompact florescent light (CFL) load.

In one embodiment, at least one load power parameter is based on acurrent propagating through the at least one electrical load.

In one embodiment, the series pass element is selected from a group ofseries pass elements including a thyristor device, a triac device, andat least one transistor device.

In one version of the embodiment, the at least one transistor deviceincludes a first MOSFET transistor coupled to a second MOSFETtransistor, the first MOSFET transistor being configured to provide theoutput power in a first half cycle of the AC power source and the secondMOSFET transistor being configured to provide the output power in asecond half cycle of the AC power source.

In another aspect, the present invention includes a method forcontrolling an electrical wiring device, the method includes the stepsof: providing a housing assembly having a plurality of terminals atleast partially disposed therein, the plurality of terminals beingconfigured to be coupled to an AC power source and at least oneelectrical load, the housing also including at least one variablecontrol mechanism coupled to the housing assembly, the at least onevariable control mechanism being configured to adjustably select a useradjustable load setting, the user adjustable load setting beingadjustable between a minimum setting and a maximum setting, the housingfurther including at least one series pass element coupled between theAC power source and at least one electrical load, the at least oneseries pass element being configured to provide output power to the atleast one electrical load in accordance with the user load setting, theoutput power being less than or equal to the AC power; entering acalibration mode when AC power is applied to at least a portion of theplurality of terminals; providing the at least one series pass elementwith an initial output power setting while monitoring at least one loadpower parameter; incrementing the initial output power setting to atleast one incremental output power setting while monitoring the at leastone load power parameter; and selecting a forward phase control mode ora reverse phase control mode based on the at least one incrementaloutput power setting or the at least one load power parameter thatresults in the at least one electrical load being energized.

In one embodiment, the method includes selecting the calibration valuesbased on which of the forward phase control mode or the reverse phasecontrol mode is selected, the selected calibration values correspondingto the minimum setting and the maximum setting.

In one embodiment, the method includes identifying a load type of the atleast one electrical load based on the at least one incremental outputpower setting and the at least one load power parameter that results inthe at least one electrical load being energized,

In one embodiment, the method includes selecting calibration valuesbased on the load type, the selected calibration values corresponding tothe minimum setting and the maximum setting.

In one embodiment, the plurality of terminals includes a neutralterminal or a ground terminal.

In one embodiment, the step of providing includes providing amicrocontroller coupled to a memory, the memory being configured tostore a plurality of characteristic load curves stored therein, theplurality of characteristic load curves including a plurality ofincremental power settings and a plurality of load power parameters,each characteristic load curve of the plurality of characteristic loadcurves correlating each load type with a predetermined incrementaloutput power setting versus a predetermined load power parameter.

In one embodiment, the step of providing includes providing a powersupply coupled to the AC power source, the power supply being configuredto provide at least one supply voltage.

In one version of the embodiment, the power supply is a half wave powersupply that is selectively coupled to the AC power source via one ofthree diodes, and wherein the plurality of terminals includes a phaseterminal, a first traveler terminal and a second traveler terminal, thepower supply being individually coupled to phase terminal, a firsttraveler terminal and a second traveler terminal by corresponding diodesof the three diodes.

In one embodiment, the step of providing includes providing a zero crosscircuit coupled to the AC power source via one of three electricalpaths, each of the three electrical paths are selectively coupled to oneof a first traveler terminal, a second traveler terminal or a phaseterminal via a diode.

In one embodiment, the method includes entering a calibration mode whenat least a portion of the at least one variable control mechanism isactuated, the portion including an ON/OFF control.

In one embodiment, the series pass element is selected from a group ofseries pass elements including a thyristor device, a triac device, andat least one transistor device.

In one version of the embodiment, the at least one transistor deviceincludes a first MOSFET transistor coupled to a second MOSFETtransistor, the first MOSFET transistor being configured to provide theoutput power in a first half cycle of the AC power source and the secondMOSFET transistor being configured to provide the output power in asecond half cycle of the AC power source.

Additional features and advantages of the invention will be set forth inthe detailed description which follows, and in part will be readilyapparent to those skilled in the art from that description or recognizedby practicing the invention as described herein, including the detaileddescription which follows, the claims, as well as the appended drawings.

It is to be understood that both the foregoing general description andthe following detailed description are merely exemplary of theinvention, and are intended to provide an overview or framework forunderstanding the nature and character of the invention as it isclaimed. It should be appreciated that all combinations of the foregoingconcepts and additional concepts discussed in greater detail below(provided such concepts are not mutually inconsistent) are contemplatedas being part of the inventive subject matter disclosed herein. Inparticular, all combinations of claimed subject matter appearing at theend of this disclosure are contemplated as being part of the inventivesubject matter disclosed herein. It should also be appreciated thatterminology explicitly employed herein that also may appear in anydisclosure incorporated by reference should be accorded a meaning mostconsistent with the particular concepts disclosed herein.

The accompanying drawings are included to provide a furtherunderstanding of the invention, and are incorporated in and constitute apart of this specification. The drawings illustrate various embodimentsof the invention and together with the description serve to explain theprinciples and operation of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings, like reference characters generally refer to the sameparts throughout the different views. Also, the drawings are notnecessarily to scale, emphasis instead generally being placed uponillustrating the principles of the invention.

FIG. 1 is a general block diagram of a universal power control device inaccordance with the present invention;

FIG. 2A-2B are block diagrams of the universal power control device inaccordance with the first embodiment, FIG. 2A is a block diagram of theAC power circuitry and FIG. 2B is a block diagram of the processing andlogic circuitry;

FIG. 3 is a detailed circuit diagram of a microcontroller circuit inaccordance with the first embodiment of the present invention;

FIG. 4 is a detailed circuit diagram of a user display circuit inaccordance with an embodiment of the present invention;

FIG. 5 is a detailed circuit diagram of a power supply in accordancewith an embodiment of the present invention;

FIG. 6 is a detailed circuit diagram of a dimmer circuit in accordancewith an embodiment of the present invention;

FIG. 7 is a detailed circuit diagram of a switch relay circuit inaccordance with an embodiment of the present invention;

FIG. 8 is a diagrammatic depiction of a load sensor in accordance withan embodiment of the present invention;

FIG. 9 is a detailed circuit diagram of a load sensor detector circuitin accordance with an embodiment of the present invention;

FIGS. 10A, 10B, 10C are diagrammatic depictions of a three-way switcharrangement in accordance with the present invention;

FIG. 11 is a block diagram of the AC power circuitry in accordance withan embodiment of the present invention;

FIG. 12 is a detailed circuit diagram of a power supply in accordancewith an embodiment of the present invention;

FIG. 13 is a detailed circuit diagram of a dimmer circuit in accordancewith an embodiment of the present invention;

FIG. 14 is a detailed circuit diagram of a switch relay in accordancewith an embodiment of the present invention;

FIGS. 15A-15B are diagrammatic depictions of another three-way switcharrangement in accordance with the present invention;

FIG. 16 is a flow chart diagram illustrating a software auto-calibrationsequence in accordance with the present invention;

FIG. 17 is a flow chart diagram illustrating a software main program inaccordance with the present invention;

FIG. 18 is a flow chart diagram illustrating a software zero crossinterrupt routine in accordance with the present invention;

FIG. 19 is a flow chart diagram illustrating a software load timerinterrupt routine in accordance with the present invention;

FIG. 20 is a front isometric view of a power control device inaccordance with an embodiment of the present invention;

FIG. 21 is a rear isometric view of the power control device depicted inFIG. 20;

FIG. 22 is a rear isometric view of the heat sink assembly of the powercontrol device depicted in FIG. 20;

FIG. 23 is a rear isometric view of the heat sink assembly and the powerhandling printed circuit board of the power control device depicted inFIG. 20;

FIG. 24 is a front isometric view of FIG. 20 with the ON/OFF actuatorcover removed;

FIG. 25 is a front isometric view of FIG. 20 with the ON/OFF actuatorcover and the dimmer cover removed;

FIG. 26 is a front isometric view of the heat sink assembly of FIG. 22disposed within the back body member;

FIG. 27 is a front isometric view of the power handling printed circuitboard of FIG. 23 disposed within the back body member of the device ofFIG. 20;

FIG. 28 is an exploded view of the power control device depicted in FIG.20;

FIG. 29 is an isometric view of the ON/OFF actuator cover depicted inFIG. 20;

FIGS. 30-31 are detailed isometric views of the dimmer actuator coverdepicted in FIG. 20; and

FIG. 32 is a cross-sectional view of the power control device depictedin FIG. 20.

DETAILED DESCRIPTION

Reference will now be made in detail to the present exemplaryembodiments of the invention, examples of which are illustrated in theaccompanying drawings. Wherever possible, the same reference numberswill be used throughout the drawings to refer to the same or like parts.An exemplary embodiment of the universal power control device of thepresent invention is shown in FIG. 1, and is designated generallythroughout by reference numeral 10.

As embodied herein, and depicted in FIG. 1, a general block diagram of auniversal power control device 10 in accordance with the presentinvention is disclosed. The device 10 includes a power handling printedcircuit board (PCB) 10-1 and a processing or logic printed circuit board10-2. The power handling PCB 10-1 is coupled to the logic PCB 10-2 by aninterface 10-3. In another embodiment of the present invention, thesecircuits are disposed on a single printed circuit board (PCB). In yetanother embodiment, for example, the power handling circuitry 10-1 isdisposed on a printed circuit board adjacent a heat sink (not shown)whereas the logic circuitry 10-2 is disposed on a second PCB disposedadjacent to a cover portion.

The power handling circuit 10-1 is coupled to AC power by way of theexternal AC terminals 12. If the device is employed as a single polesingle throw (SPST) switch, the power control device is coupled to thehot connector (black) and inserted between the AC power source and theload to provide the load with variable power (e.g., dimmed power in alighting application). The power control device 10 may also be employedin three-way switching arrangements. In this case, the device 10provides terminal connections for a hot (or load) wire, a first travelerwire and a second traveler wire. In many retrofits, the device box maynot have a neutral wire; in newer construction, or in newer retrofits,the device box may include a neutral wire. The present invention canaccommodate a neutral wire and may also include a ground wire in atleast one embodiment.

The power supply 20 is configured to rectify the AC power derived fromterminals 12 to provide a high voltage DC supply for the relay circuit40 and a +5 VDC supply for use by the logic circuitry 10-2. The powersupply 20 further provides a zero-cross signal which is used by theprocessing circuitry 110 for timing purposes. The power handling circuit10-1 also includes a load sensor 50 that is configured to provide theprocessing circuitry 110 with load current data. In one embodimentdescribed below, the processing circuit 110 is configured to determinethe type of lighting device that is installed by monitoring the loadcurrent data to determine whether the device 10 should operate usingforward phase control or reverse phase control. Similarly, theprocessing circuit 110 also monitors the load current data to determinean optimal dimming voltage range for the specific lighting device type.In another embodiment described below, the processor can determine thedimming voltage range by monitoring the supply voltage when a ground orneutral wire is present. In another embodiment, this dimming range datais provided by the user via inputs 120 disposed in the logic circuitryportion 10-2 of the device 10.

The user input circuitry 120 provides the processing circuitry 110 withinformation that includes, among other things, lighting device type,calibration commands, load ON/OFF commands, and dimmer setting inputs.The processing circuitry 110 is configured to actuate the relay circuit40 to turn the load ON or OFF based on user commands. The processingcircuit 110 also provides the dimmer circuit 30 with dimmer commands inaccordance with the user inputs and the load sensor 50 input. The dimmercircuit, of course, provides a dimmed power signal to the load via theAC terminals 12. As those skilled in the art will appreciate, dimming isaccomplished in the reverse phase by switching the load current ON whenthe zero-crossing of the AC half-cycle is detected by the powerdetecting circuit 10-1 and turned OFF at a user adjustable phase angle.Conversely, in forward phase control, the load current is turned ON atthe user adjustable phase angle and turned OFF when the next zerocrossing is detected by the power detecting circuit. As those skilled inthe art will appreciate, forward phase control is appropriate forconventional incandescent lighting, magnetic low voltage (MLV) lightingfixtures, conventional fluorescent lighting fixtures employingelectronic ballasts (EFL), and halogen lighting. Reverse phase controlis generally appropriate for electronic low voltage (ELV) lighting.Bulbs designed as higher efficiency 120V incandescent replacements,including LED bulbs and compact florescent lights (CFL) typicallyperform better with forward phase control. One of the universalityfeatures of the present invention is that the dimmer circuit may beemployed in forward phase for certain optimized ELV, CFL and LEDdevices.

It will be apparent to those of ordinary skill in the pertinent art thatmodifications and variations can be made to the processing circuitry 110of the present invention depending on the degree of processingsophistication provided in a given device. The processing circuitry 110may employ random access memory (RAM), read only memory (ROM), I/Ocircuitry, and communication interface circuitry coupled together by abus system. The buss typically provides data, address, and control linesbetween a processor and the other system components. Moreover, processorfunctions may be implemented using hardware, software, general purposeprocessors, signal processors, RISC computers, application specificintegrated circuits (ASICs), field programmable gate array (FPGA)devices, customized integrated circuits and/or a combination thereof.Thus, embodiments of the present invention are not limited to anyspecific combination of hardware circuitry and/or software. Takentogether, RAM and ROM may be referred to herein as “computer-readablemedia.” The term “computer-readable medium,” as used herein, refers toany medium that participates in providing data and/or instructions tothe processor for execution. For example, the computer-readable mediaemployed herein may include any suitable memory device including SRAM,DRAM, NVRWM, PROM, E²PROM, Flash memory, or any suitable type of memory.In one embodiment, data and instructions may be provided to device 10via electromagnetic waves. The processing circuitry 110 provides dimmerstatus information to the output display 130 such as the dimmablesetting, lamp type, or user instruction.

As embodied herein, and depicted in FIG. 2A, a block diagram of the ACpower handling circuitry 10-1 in accordance with an embodiment of thepresent invention is disclosed. The terminals include a hot/loadterminal 12-1, traveler terminal 12-2, traveler terminal 12-3 andneutral terminal 12-4. The neutral terminal 12-4 is employed as a meansfor referencing ground. In another embodiment of the invention (notshown), the terminals include a ground terminal to which the groundconductor of the electrical distribution system is connected. The groundterminal is also used, of course, to reference ground potential. Inanother embodiment both a ground terminal and a neutral terminal areprovided and the ground reference is associated with either terminaldepending on whether the neutral conductor or ground conductor isprovided by the electrical distribution system. In each of theseembodiments, the device 10 also includes the traveler terminals (12-2,12-3) for use in three-way switch arrangements. The hot/load terminal12-1 may be connected to the hot terminal of the AC power source, or tothe load. This capability is a feature of the power supply circuit 20and the dimmer circuit 30 described below.

In one embodiment of the present invention, the interface device 10-3 ismounted on the power handling PCB 10-1 and is used to communicate powerand logic signals between the PCB 10-1 and the PCB 10-2. In addition,the power supply 20 provides +5 VDC and a reference ground connectionvia device 10-3. The power supply 20 provides the processing circuitry110 with the zero cross signal (ZC), and the load sensor 50 provides theprocessor circuitry with a sensor input (I sns) via an interface device10-3. The processing circuitry 110 provides the relay control signals(RC1, RC2) and the dimmer control signal (PWM) via the interface 10-3.

As embodied herein, and depicted in FIG. 2B, a block diagram of thelogic PCB 10-2 in accordance with one embodiment of the invention isdisclosed. The logic PCB 10-2 includes interface pins 10-20 that matewith the interface device 10-3 (FIG. 2A) to complete the bi-directionalcommunication path between the power PCB 10-1 and the logic PCB 10-2. Asnoted above, power signals are conducted from the power handling circuit10-1 to the logic circuit 10-2, and the logic signals are conducted fromlogic circuit 10-2 to the power handling circuit 10-1 as appropriate.The load sensor detection circuit 112 employs the load sensor 50 signal(I Sns) to generate a sensor detection signal (I SNS AMP OUT) for use bythe processor circuitry 110. And as further shown in FIG. 2B, theprocessor circuit 110 provides the relay commands (RC1, RC2) and thedimmer command (PWM) to the power circuit 10-1 via the interface pins10-20. The processor circuit 110 also provides output data to thedisplay circuit 130 which is also disposed on the logic PCB 10-2.Although they are not shown in FIG. 2B, the processor circuit 110 isalso connected to user-accessible input devices that convert usercommands into electronic commands. The user commands may be provided tothe processor circuit by way of, but not limited to, switches, buttons,electromagnetic signals (e.g., RF or optical) that may originate from akeyboard, mouse, or by voice commands.

As embodied herein and depicted in FIG. 3, a detailed circuit diagram ofa microcontroller circuit 110-1 in accordance with another embodiment ofthe present invention is disclosed. The processor circuit 110 isimplemented using a microcomputer 110-1 which is selected based on acombination of characteristics including performance, cost, size andpower consumption. In other words, the present invention contemplates avariety of models that provide the consumer with options that areclosely suited to the consumers' needs and desires. The term“microcomputer performance” refers to an optimal combination ofprocessing speed, memory size, I/O pin capability, and peripheral setcapabilities (e.g., A/D converter, comparators, timers, serial bus,etc). As those skilled in the art will appreciate, any suitableprocessing device may be employed. In one embodiment of the presentinvention, the microcomputer is implemented by a device known as the“ATtiny44a”, which is manufactured by the Atmel Corporation. In anotherembodiment, the microcomputer is implemented using Atmel's “ATtiny84a”because the latter device offers more program memory than the former(i.e., 44a). Specifically, the ATtiny 84a includes 8 kB of programmemory whereas the ATtiny 44a includes 4 kB of program memory. In oneembodiment, the central processing unit (CPU) is operated at a clockfrequency that is well below its rated frequency to thereby minimizepower consumption.

It will be apparent to those of skilled in the pertinent art thatmodifications and variations can be made to the processor circuit 110 ofthe present invention depending on the amount and sophistication offeatures that are provided to the user. As noted previously, anysuitable arrangement of hardware and/or software may be employed giventhe size constraints of an electrical wiring device. Thus, processorcircuit 110 may be implemented using general purpose processors, signalprocessors, RISC computers, application specific integrated circuits(ASICs), field programmable gate array (FPGA) devices, customizedintegrated circuits and/or a combination thereof. With respect to themicrocomputer 110-1 depicted in FIG. 3, any suitable microcomputer maybe employed including, but not limited to those selected from theMicrochip PIC12F family, the Freescale HC08 family, the TexasInstruments MSP430 family, or the ST Micro STM8 family (in addition tothe Atmel devices described previously).

Turning now to FIG. 3 in more detail, a description of the data signalsused, and provided by, microcontroller 110-1 is provided to aid thereader's understanding of this embodiment of the present invention. The“nReset” signal is generated after power is removed from the device andsubsequently reapplied. This signal causes the device to re-performcalibration before providing service. In this embodiment, themicrocomputer 110-1 is connected to three user-operated buttons(“ON/OFF” button 120-1, “Down Button” 120-2, and “UP Button” 120-3). Asshown, each button circuit is pulled to a logic high (+5V) by a 100Kpull-up resistor. When a user depresses a button, its correspondingswitch (S200, S201, S202) is closed to ground the circuit such that themicrocomputer reads a logic zero (0 V) to indicate that the user hasmade a command. With respect to the ON/OFF button 120-1, if the currentstate of the wiring device is “OFF,” an actuation of the button 120-1directs the microcontroller to send a signal via lines RC1, RC2 suchthat the relay turns the load “ON.” When the user depresses the button120-1 again, the same sequence plays out such that the relays turn theload “OFF.” The “down button” circuit 120-2 and the “up button” circuit120-3 operate in the same identical way that the ON/OFF button operates.An actuation of the up-button 120-3 is interpreted as a command toincrease the power delivered to the load, and an actuation of thedown-button 120-2 is just the opposite.

In particular, when the down-button 120-2 is depressed, the software inthe microcontroller changes the PWM signal that drives the dimmercircuit 30 so that the lighting load is incrementally dimmed. (Ofcourse, the circuit may also be used to slow an electric motor, e.g., afan motor). Conversely, when the up-button 120-3 is depressed, thesoftware in the microcontroller changes the PWM signal that drives thedimmer circuit 30 so that the lighting load is incrementally raised.With respect to button 120-3, the programming header 120-4 allows aperson having the appropriate skill level to reprogram and/or debug themicrocomputer 110 when button 120-3 is depressed in a predeterminedsequence. The sequence is an indication to the microcomputer 110-1 thata data input device (a host computer interface, RF interface, keyboard,etc.) is being connected to header 120-4 and a reprogramming sequence isbeing initiated. The microcontroller 110-1 is also connected to thedisplay circuit (shown in FIG. 4) by a serial clock signal (SCL) and aserial data signal (SDA) to provide a serial bit stream that correspondsto the appropriate device display settings (which are described below inconjunction with the circuit depicted in FIG. 4). The display settingsare transmitted to the display circuit 130 when the settings are changedby a user input command and refreshed periodically. In one embodiment ofthe present invention, the microcomputer refreshes the settings every300 msec, or at a 3.3 Hz rate. Of course, any suitable refreshing ratemay be selected depending on the processor load.

The zero cross signal (ZC) is provided by the power PCB 10-1 and ispaired with the VREF FOR Z-CROSS signal. These signals comprise adifferential input signal that is provided to a differential comparatordisposed inside the microcomputer 110-1. The differential signaleliminates common-mode noise to prevent any false zero cross detectionsby the microcomputer 110-1. Stated differently, the reference timingprovided by the zero cross detector of the present invention issubstantially immunized from common mode noise to substantiallyeliminate spurious timing signals. The purpose and function of theremaining signals will become apparent when their corresponding circuitsare described herein.

Referring to FIG. 4, a detailed circuit diagram of a user displaycircuit 130 in accordance with an embodiment of the present invention isdisclosed. As alluded to above, the signals SCL and SDA are provided toan I/O expander circuit 130-1 in display circuit 130. The I/O expander130-1 is configured to receive the serial bit stream (SDA) from themicrocomputer 110-1 and convert it into a parallel data output for useby the display LEDs 130-2, 130-3, 130-4 and 130-5. In the embodiment ofFIG. 4, seven (7) bar graph LEDs 130-2 are included to provide the userwith an indication of the dimmer setting. For example, if one LED is ONand the other six LEDs are OFF, the bar graph indicates to the user thatthe light level setting is at its lowest setting. Conversely, if allseven (7) LEDs in the bar graph 130-2 are illuminated, the dimmer is atits highest setting.

The LEDs 130-3, 130-4, and 130-5 work in conjunction with the transistor130-6. When the lighting load or the motor load is turned OFF by therelay circuit 40, the microcomputer transmits an appropriate bit commandsuch that transistor 130-6 is turned ON. This causes current to flowthrough the locator LED 130-5. Once the lighting load is turned OFF, theLED 130-5 is turned ON to provide the user with a relatively smalllocator light that tells the user where to find the light switch in thedarkened room. When current flows through LED 130-5, however, currentcannot flow through the (−) LED 130-3 and the (+) LED 130-4 because bothof these LEDs are biased OFF. In other words, these LEDs are presentedwith the same voltage potential at their anodes and cathodes such thatcurrent cannot flow. The purpose of the (−) LED and the (+) LED displaysis to direct the user to the down button 120-2 and the up button 120-3,respectively. When the load is turned OFF, the dimming function isirrelevant and the −LED and the +LED are OFF to further indicate thatthe load is OFF.

Referring to FIG. 5, a detailed circuit diagram of the power supplycircuit in accordance with an embodiment of the present invention isdisclosed. The power supply includes a half-wave rectifier circuit thatis comprised of diodes 200-202. The half-wave rectified DC signal isshown as HVDC. The half-wave rectified signal HVDC is employed by theregulator circuit 20-1 to further provide the power supply referencesignals +5V and ground (GND) for the processor circuit 110.

The diodes 200-202 are disposed in parallel with each other so that theAC power signal may be provided to the power supply via the hot/load pinor by either of the traveler pins (T1, T2). The utility of this parallelarrangement becomes more apparent in FIGS. 10A-10C and the descriptionthereof. Needless to say, this feature yields a universal dimmer thatcan be placed in either switch position of a retrofit three-way switcharrangement. Regardless of the switch position, or which traveler pinthe relay circuit 40 is connected, one of diodes 200-202 will furnishcurrent to the power supply. Note also that diodes 204-206 (as a group)are placed in parallel with diodes 200-202 to provide the zero crossdetector 20-2 with the half-wave rectified DC signal so that the zerocross detector 20-2 provides the zero cross (ZC) signal described above.Diodes 204-206 are also disposed in parallel with each other (likediodes 200-202) so that AC power signal may be provided to thezero-cross detection circuit 20-2 via the hot/load pin or either of thetraveler pins (T1, T2). Regardless of the switch position, or whichtraveler pin the relay circuit 40 is connected to, one of diodes 204-206will furnish current to the zero-cross detection circuit.

Referring to FIG. 6, a detailed circuit diagram of the dimmer circuit inaccordance with the present invention is disclosed. The microcomputer110-1 controls the dimmer circuit 30 by way of the pulse widthmodulation (PWM) signal. Specifically, the PWM signal propagates atlogic levels (+5V, GND) and controls the operation of transistor 30-1.The width of the PWM pulse is varied to control the amount of powerprovided to the load, whether a lamp load or a motor load. The PWMsignal comprises at least one pulse in an AC line cycle. In oneembodiment of the invention, the PWM signal may provide a plurality ofpulses within an AC half cycle. By using pulse width modulation, thepresent invention may be used as a universal dimmer device that cancontrol any type of lighting load by varying the duty cycle of the pulserelative to the zero cross. In operation, when the PWM signal is high,the transistor 30-1 conducts through the opto-coupler 30-2 to turntransistors 30-3 and 30-4 ON in accordance with the appropriate timing.Note that for the MOSFET implementation shown in FIG. 6, two transistors(30-3, 30-4) are required for operation. This is due to the internalbody diode inherent in MOSFET technology; one MOSFET blocks a portion ofthe positive AC half cycle, and the other blocks a portion of thenegative half-cycle to the load. The timing of the PWM pulse is ofcourse controlled by the microcomputer and it is timed relative to thezero crossing of the AC cycle. As noted above, dimming is accomplishedin the forward phase by switching the load current ON sometime after thezero-crossing of the AC half-cycle and turned OFF at the nextzero-crossing of the AC waveform. Conversely, in reverse phase control,the load current is turned ON when the zero-crossing is detected andturned OFF sometime before the next zero-crossing is detected.

Because the PWM pulse is controlled by the microcomputer 110-1 (with ahigh degree of granularity) while simultaneously monitoring the loadcurrent, the dimmer circuit may employ forward phase control to drivecertain optimized ELV, CFL and LED devices. At the outset of theprocess, the microcontroller transmits a PWM signal at a very low dutycycle and increases the duty cycle incrementally until the I SNS AMP OUTsignal (from the load current detector 112) indicates that there is aload current being drawn. If the fixture is an incandescent one, theload current in this region (low duty cycle) is substantially linearwith respect to the PWM duty cycle. If the fixture is an LED fixture,the load current will not be present until the duty cycle has beenincreased to a certain threshold. Thus, the present invention employs acontrol loop that optimizes the PWM duty cycle for any given lightingload. Moreover, the microcomputer 110-1 may adjust the PWM signal tooperate in forward phase or reverse phase by operation of the software.Again, as those skilled in the art will appreciate, forward phasecontrol is appropriate for conventional incandescent lighting, magneticlow voltage (MLV) lighting fixtures, conventional fluorescent lightingfixtures employing electronic ballasts (EFL), and halogen lightingdevices. Reverse phase control is generally appropriate for electroniclow voltage (ELV) lighting. Bulbs designed as higher efficiency 120Vincandescent replacements, including LED bulbs and compact florescentlights (CFL) typically perform better with forward phase control.

In one embodiment of the present invention, thermal sensors (Ts) 52 and54 measure the heat being generated by the MOSFETs to obtain an estimateof power consumption. Thus, the sensor 52 is positioned proximate thetransistors 30-3, 30-4 to obtain a measurement of the heat beinggenerated thereby. The second sensor 54 is disposed in a region of thedevice that experiences the ambient temperature of the device 10. Themicrocomputer 110-1 is programmed to calculate the temperaturedifference to determine the amount of thermal energy generated by thetransistors 30-3, 30-4. As those skilled in the art will appreciate,there is a relationship (I²R) between the dissipated heat and the power.

(Again, with respect to FIGS. 10A-10C, the AC signal may be provided viathe HOT/LOAD terminal and the dimmed signal by way of the SWITCH POLEterminal, or vice-versa, depending on which switch position the device10 occupies in the three-way arrangement). Finally, note that wire-loop50-1 is connected between transistor 30-4 and the SWITCH POLE terminal.The wire loop passes through the current sensor toroid 50 depicted inFIG. 8.

Referring to FIG. 7, a detailed circuit diagram of the switch relaycircuit 40 in accordance with an embodiment of the present invention isdisclosed. Again, the latching relay 40-1 may be configured to supportboth SPST applications as well as single pole double throw (SPDT)applications. In the SPDT application the relay 40-1 is moved between afirst switch position that connects T1 and SWITCH POLE, and a secondswitch position that connects T2 with SWITCH POLE. The relay commandsignals RC1 and RC 2 are logic level signals that control transistors40-3 and 40-2, respectively. If the latching relay is in the firstswitch position, the microcontroller 110-1 will provide a pulse via therelay command signal RC2 to cause the switch 40-1 to toggle into thesecond switch position. Conversely, if the latching relay is in thesecond switch position, the microcontroller 110-1 will provide a pulsevia relay command signal RC1 to cause the relay 40-1 to toggle back intothe first switch position.

Referring to FIG. 8, a diagrammatic depiction of the load sensor 50 inaccordance with the present invention is disclosed. As noted above, awire loop connected to the SWITCH POLE terminal is disposed through thecenter of the toroid to create a transformer circuit. The wire loop 50-1carries the load current and functions as the transformer primary. Thecurrent sensor 50 may also be implemented as a toroid.

Referring to FIG. 9, a detailed circuit diagram of a load sensordetector circuit 112 in accordance with the present invention isdisclosed. In this embodiment the detector 112 is configured as athreshold detector 112-1 that compares the I SNS signal from sensor 50described above, with a predetermined threshold value. In thisparticular embodiment, the detector 112-1 provides a logic signal to themicrocomputer 110-1. In one embodiment, if the load current is greaterthan about 10 mA, the detector 112-1 is configured to provide a logicone (+5V) signal. If the load current is below the threshold, a logiczero (0 V) is provided. Those skilled in the art will appreciate thatthe threshold level is adjustable and depends on the level ofsensitivity desired and the type of load. In this embodiment, themicrocomputer 110-1 is signaled by I SNS AMP OUT when a minimal amountof current is being drawn by the load.

As embodied herein and depicted in FIGS. 10A-10C, diagrammaticdepictions of a three-way switch arrangement in accordance with thepresent invention are disclosed. FIG. 10A shows a typical three-wayswitch arrangement wherein the line voltage (i.e. 120 VAC) is connectedto the pole of a first SPDT switch S1 and the load is connected to thepole of a second SPDT switch S2. In this diagram, the load L is ON byvirtue of the switch positions of S1 and S2. Toggling either S1 or S2into a second switch position will turn the load OFF. The presentinvention may replace either one of the switches S1 and S2.

FIG. 10B shows device 10 of the present invention being connected toswitch S1 in FIG. 10A. Thus, the hot AC line signal is directed into thedimmer/latching switch 30/40 via the T1 terminal, and further directedinto the regulator 20-1 via diode 200 and the zero-cross detector 20-2via diode 204. The dimmed power is provided to the load via the HOT/LOADterminal. If the device 10 is switched such that AC power is providedvia the T2 terminal, the diode arrangement (201,205) ensures that ACpower is directed to the regulator and the zero-cross detector.

FIG. 10C shows device 10 of the present invention being connected toswitch S2 in FIG. 10A. In this configuration, the AC hot is directedinto the dimmer/relay circuits 30/40 via the relay pole line; dimmedpower is provided to the load via terminal T1. Because of the diodecircuit described previously, AC hot is provided to the regulator 20-1via diode 202 and to ZC Detector 20-2 via diode 206.

As embodied herein and depicted in FIG. 11, a block diagram of the ACpower circuitry in accordance with another embodiment of the presentinvention is disclosed. This embodiment is identical to the one depictedin FIG. 2A with the exception that there is no neutral terminal orground terminal available for circuit reference. Thus, this device 10may be employed in a retrofit/remodeling project where the existingdevice box does not include a neutral conductor.

Referring to FIG. 12, a detailed circuit diagram of the power supplydepicted in FIG. 11 is disclosed. Because there is no neutralconnection, two less diodes are required. The zero-cross detectioncircuit 20-2 is essentially the same as the one depicted in FIG. 5. Thelinear regulator circuit produces a virtual ground node approximately24V below the Hot/Load terminal. D203 is biased with R200 and R201 toproduce 24V, and Q200 provides current amplification and improved loadregulation compared with a zener regulator acting alone. U200 furtherregulates the 24V down to 5V for use by the dimmer control circuitry.R202-R205 provide current limiting in the event of a short circuit onthe 24V or 5V supplies.

Referring to FIG. 13, a detailed circuit diagram of the dimmer circuit30 depicted in FIG. 11 is disclosed. As before, the microcomputer 110-1controls the dimmer circuit 30 by way of the PWM signal. The PWM signalis at logic levels (+5V, GND) and controls the operation of transistor30-1. When transistor 30-11 is turned ON at a predetermined point in theAC half cycle, an appropriate amount of current is provided to the triac30-10 to turn it ON such that dimmed power is provided to the load.L300, R300, and C300 implement RFI filtering to minimize electromagneticinterference into nearby electronic equipment.

Referring to FIG. 14, a detailed circuit diagram of the switch relaydepicted in FIG. 11 is disclosed. This circuit is identical to the onedepicted in FIG. 7, and therefore, no further description is requiredwith the exception that the transistors 40-2 and 40-3 are connected tothe HOT/LOAD terminal instead of the rectified HVDC signal (FIG. 7). Asstated previously, the circuit's ground reference is 24V below theHot/Load terminal; therefore this configuration provides 24V for drivingthe relay coil.

As embodied herein and depicted in FIGS. 15A-15B, diagrammaticdepictions of another three-way switch arrangement in accordance withthe present invention are disclosed. These diagrams illustrate that theembodiment of FIG. 11 may replace either switch S1 or switch S2 in FIG.10A. This capability is enabled by the diode arrangement 200-203 and theanalysis is similar to the one provided in conjunction with FIGS.10A-10C.

As embodied herein and depicted in FIG. 16, a flow chart diagramillustrating a software auto-calibration sequence 1600 in accordancewith the present invention is disclosed. In step 1602 the device isenergized and in step 1604 the microcontroller sets the duty cycle ofthe PWM pulse at an initial value that may be thought of as an idlingvalue. In step 1606, the microcomputer 110-1 waits a predetermined timeto determine if the load current is detected. In steps 1608-1612, thePWM pulse width is increased until either the load current is detectedor a maximum width value is exceeded. If the maximum width value isexceeded, the microcontroller 110-1 assumes that the load is turned OFFby the companion switch (S1 or S2) and goes back to the initial PWMsetting in step 1604. The cycle is repeated until the load current isdetected in step 1614. The microcontroller 110-1, of course, knows thePWM value when load current is detected. (As noted below, themicrocontroller 110-1 may include PWM v. load current curves that can beused to identify a given load).

Load current detection is achieved when the threshold detector 112-1finds that the I SNS signal from sensor 50 reliably exceeds thethreshold. In one embodiment, I SNS is sampled 1000 times over a second.If at least 800 of the samples do not indicate load presence, the lampis either OFF or flickering; and the microcontroller 110-1 increases thePWM width in accordance with an approximately 10 VRMS step increase involtage to the lamp. This process of checking the threshold detector andwidening the PWM step is iterated until the lamp is either reliably ON(i.e., at least 800 samples are detected to indicate the presence of theload) or the maximum width is exceeded. The microcontroller ceases theiterative process when about 70 VRMS is provided to the load.

The automatic calibration process (steps 1602-1628) can be accomplishedin a matter of seconds. In one embodiment the calibration is initiatedwhen an upstream breaker is opened momentarily and then closed torestore the voltage on the dimmer's power supply. In another embodiment,the automatic calibration takes place when a button on the dimmer isactuated by the user. In another approach, the automatic calibrationtakes place each time a switch is toggled to apply power to the load.When the load current is detected in step 1614, the microcontroller110-1 uses the output voltage as the starting output voltage for thelower calibration level (in step 1616).

The voltage at which the lamp is reliably ON is indicative of the typeof load in use. For example, if the absolute value of the load currentis low, it may indicate that the load is an LED lamp. As anotherexample, the microcontroller 110-1 is configured to track the number ofload indication samples in a given measurement interval and determinethe type of load by noting the change (the number of load indicationsamples) from interval to interval. In the subsequent steps (1618-1628),the microcontroller 110-1 continues to incrementally increase thevoltage until the estimated power (based on the sensed current) exceedsan upper threshold (1620) for the load; this value is used to find theupper calibration value (1626). The calibration values are stored inmemory (step 1628) for use by the microcontroller 110-1.

The microcontroller 110-1 is configured to determine that the lightingdevice is a capacitive load device when it detects current spikes in aforward phase mode. Conversely, the microcontroller 110-1 will detectcurrent spikes when an inductive load is when the dimmer is operating ina reverse phase mode.

The microcontroller 110-1 is configured to determine the type of loadbased on whether or not there is an inrush current when the load isturned ON. The microcontroller 110-1 may be configured to compare theinrush characteristics of a given load to in-rush curves stored inmemory (e.g. the characteristic curve for a tungsten filament load).Unlike traditional incandescent bulbs, modern high-efficiency bulbs suchas CFLs and LEDs do not turn on smoothly when the terminal voltage isincreased from zero volts. Rather, these bulbs will not conduct (turnON) until a specified voltage is applied (i.e., the specified voltage isa function of the bulb design). For example, one manufacturer's LED bulbmay be configured to turn ON at 40Vrms, while another manufacturer's LEDbulb may turn ON at 60Vrms. Additionally, if the bulb voltage ismaintained at or near the bulb's turn ON voltage, the bulb may flash(flicker). (Hence, the microcontroller 110-1 can perform the calibrationroutine at steps 1602-1628 based on the curves stored in memory).

When high-efficiency bulbs (e.g., LEDs, CFL, etc.) are used, thedimmer's output voltage should not drop below a stable turn-on voltagespecified for the bulb. Dimmers designed for use with high-efficiencybulbs are typically calibrated at the factory so that the bulb operatesat a specified low-end voltage based on the type of high-efficiency bulbthe dimmer is designed for. On the other hand, when the intended use ofa dimmer contemplates using various kinds of load types, a number ofcalibration strategies must be considered. For example, one calibrationstrategy that may be considered includes setting the minimum dimmeroutput voltage to a relatively level so that all types of bulbs willturn ON without flashing. This procedure can be done duringmanufacturing. The downside of this approach is that the resultingdimming range will be unacceptably narrow for many load types. A designapproach that can be considered includes providing the dimmer with amanual calibration feature that allows the end user to calibrate thedimmer after installation. One drawback to this approach is that theuser/installer must perform an additional procedure after dimmerinstallation. This approach may result in unacceptable dimmer operationif the user fails to perform the calibration properly. (This may occurif the instructions are poorly written, the user/installer fails tofollow the instructions, or both).

Instead of using the aforementioned approaches, the present inventionembeds a calibration algorithm into the dimmer so that themicrocontroller 110-1 automatically calibrates the dimmer for the loadbeing used. As noted above, auto-calibration can occur when power isfirst applied to the dimmer after installation. (The instant disclosurealso teaches that the calibration algorithm can be performed when: (1)an upstream breaker is momentarily opened and re-closed; (2) when abutton on the dimmer is actuated by the user; and/or each time a switchis toggled to apply power to the load). In reference, e.g., to FIG. 16,the dimmer of the present invention implements the auto-calibrationfeature by automatically increasing the dimming voltage in predeterminedincrements while estimating the power being delivered to the load ateach increment. (See steps 1602-1622 at FIG. 16). When themicrocontroller 110-1 senses a sudden increase in sensed current, i.e.,the microcontroller 110-1 detects the load, it performs theauto-calibration routine by setting the incremental dimmer voltage atthe lower calibration value (see, e.g., steps 1614-1616 at FIG. 16). Asexplained above, the memory of the microcontroller 110-1 can include alook-up table that has load (bulb) characteristic curves based on theinitial sensed load current vs. load turn-on voltage. At this point, thecalibration routine continues to sense the load current for eachincremental output voltage until the load power reaches the upperthreshold value.

As noted herein (above and below), one embodiment of the presentinvention uses a current sensor to estimate load power, andmicrocontroller 110-1 to perform the calibration routine and control thedimming. This implementation is suitable for use in either single poleor 3-way switch installations.

As embodied herein and depicted in FIG. 17, a flow chart diagramillustrating a main software program is disclosed. After initializationand calibration (1702), the microcomputer 110-1 reads and records (instep 1704) the user input from, e.g., the button inputs describedherein. (See, e.g., FIG. 3). If an ON/OFF command is issued by the user,the microcomputer 110-1 directs the relay circuit 40 accordingly. Afterdetermining if a load current is present (step 1708), the computer 110-1adjusts the PWM dimmer setting in accordance with user commands (1710)and updates the display LEDs (1712) accordingly. This process isperformed continually thereafter.

As embodied herein and depicted in FIG. 18, a flow chart diagram 1800illustrating a software zero cross interrupt routine 1800 is disclosed.In step 1804, the microcomputer 110-1 determines whether device 10should operate in forward phase control (FPC) or in reverse phasecontrol (RPC) using any one of the methods described herein. In theforward phase, the load current is switched ON a predetermined timeafter the zero-crossing of the AC half-cycle and turned OFF at the nextzero-crossing of the AC waveform. Conversely, in reverse phase control,the load current is turned ON immediately after the zero-crossing isdetected and turned OFF at a predetermined time before the nextzero-crossing is detected. The predetermined time intervals describedabove can be implemented by scheduling a software load timer interrupt.

As embodied herein and depicted in FIG. 19, a flow chart diagram 1900illustrating a software load timer interrupt routine is disclosed. As anextension to discussion on FIG. 18 above, the load timer interrupt turnsthe load current off when operating in reverse phase, and turns the loadcurrent on when operating in forward phase.

As embodied herein and depicted in FIG. 20, a front isometric view of apower control device 10 in accordance with an embodiment of the presentinvention is disclosed. Device 10 includes a switch cover 204 disposedon heat sink assembly 202. The power handling PCB 10-1 is disposed underthe heat sink 202 and within the back body member 200. FIG. 21 is a rearisometric view of the power control device depicted in FIG. 20 and showsthe back body member 200 and the heat sink 202.

Referring to FIG. 22, a rear isometric view of the heat sink assembly ofthe power control device depicted in FIG. 20 is disclosed. In this view,the back body member 200 is removed so that the internal components maybe seen. Specifically, the separator member 202-2 is shown as beingconnected to the front of the heat sink 202. The pins of the MOSFETs30-3, 30-4 and the interface circuit 10-3 are shown as extending throughthe separator 202-2 so that they may be coupled to the PCB 10-1.

In FIG. 23, another rear isometric view of the heat sink assembly isshown. Again, the back body member 200 is removed so that the internalcomponents may be seen. Moreover, the power handling printed circuitboard 10-1 is added to the components shown in FIG. 22. In this view,the sensor 50, the sensor wire 50-1, the relay 40 and various othercomponents are shown as being disposed on the power handling PCB 10-1.Note that ground clip spring 202-1 is attached to the rear side of theheat sink 202. The spring clip 202-1 is configured to engage a frontportion of a frame assembly (not shown in this view). Reference is madeto U.S. patent application Ser. No. 13/680,675, which is incorporatedherein by reference as though fully set forth in its entirety, for amore detailed explanation of A MODULAR ELECTRICAL WIRING DEVICE SYSTEMand the associated framing system.

Referring to FIG. 24, a front isometric view of the device depicted inFIG. 20 is disclosed. In this view, the aesthetic cover 204 removed.Thus, the switch actuator 204-2 is shown to include a central aperturethat accommodates the locator LED 130-5. Note also that the dimmer coverassembly 206 is seated within a portion of the switch actuator 204-2.FIG. 25 is a front isometric view of FIG. 20 with the aesthetic actuatorcover 204 and the dimmer cover 206 removed; thus, the dimmer controlswitches 120-2, 120-3 are visible in this view. Snap elements 202-3 areformed in the separator 202-2 and are use to engage the dimmer cover 206and secure it to the assembly. Snap elements 202-3 are also pivot pointsthat allow the dimmer cover 206 to rotate in order to actuate dimmercontrol switches (120-2, 120-3).

Referring to FIG. 26, a front isometric view of the heat sink assemblydisposed within the back body member 200 is shown. Note that the logicPCB 10-2 is mounted to the front side of the heat sink 202. Themicrocomputer 110-1 is mounted on the PCB 10-2. The switches 120-1,120-2 and 120-3, as well as LED indicators 130-2, are also mounted onthe PCB 10-2.

Referring to FIG. 27, a front isometric view of the device is shown(with the heat sink 202 removed). In this view, the separator member202-2 can be clearly seen. This view also shows the MOSFETS 30-3 and30-4 being electrically connected to the PCB 10-1 and extending throughthe openings in the separator 202-2. The snap elements 202-3 are alsoclearly shown in this view; and as noted above, the snap elements 202-3accommodate corresponding snap-in elements that are formed in the dimmercover 205 (not shown). The separator 202-2 also includes trunions 202-4at either end. The trunions 202-4 accommodate the snap-openings 204-12in the functional actuator 204-2 (See FIG. 29). Trunions 202-4 allow thefunctional actuator 204-2 to rotate; the rotation of the functionalactuator 204-2 allows switch 120-1 to be engaged. Finally, the separator202-2 includes a spring arm 202-5 that is configured to bias thefunctional actuator 204-2 upwardly.

Referring to FIG. 28, an exploded view of the power control devicedepicted in FIG. 20 is disclosed. The device 10 includes an aestheticcover 204 that includes an LED lens 204-1 disposed in a central portionthereof. In an embodiment of the invention, lens 204-1 is a thin sectionof cover 204. The aesthetic cover further includes an opening 204-6 thataccommodates the dimmer switch cover 206. The dimmer switch cover 206includes a light pipe structure 206-1 that is held in place within thedimmer cover 206 by an alignment mask 206-2. The dimmer cover 206, thelight pipe 206-1 and the alignment mask 206-2 are configured to bedisposed within opening 204-5 formed in one side of the functionalswitch actuator 204-2. The functional switch actuator 204-2 includes acentral opening 204-3. The logic PCB 10-2 is shown over top of the frontside of the heat sink 202. The two MOSFETs 30-3 and 30-4 are coupled tothe bottom of heat sink 202 by insulator members 30-3, 30-40,respectively. Of course, the MOSFETs 30-3 and 30-4 are electricallyconnected to the power handling PCB 10-1 via openings in the separator202-2. The entire assembly is disposed within back body member 200. See,e.g., FIGS. 24-27.

Referring to FIG. 29, a bottom isometric view of the functional actuator202-2 is disclosed. The central portion of the functional switch 204-2includes a central opening 204-3 that may accommodate an LED. At oneside of the functional switch 204-2 there are snap-in elements (204-10,204-11) that are configured to mate with the snap-elements 202-6 formedin the separator. (See FIG. 27). The snap-in elements (204-10, 204-11)are bearing surfaces for the springs 202-6, and also serve to limit thespring-biased rotation. Recessed surface 204-13 engages the switch 120-1when the cosmetic actuator 204 is depressed, and it opposes the springbiased rotation. At the opposite side, trunion mounts 204-12 accommodatethe trunions 202-4 formed in the separator 202-2. The trunions 202-4allow the functional switch 204-2 to move in the process of manuallyactivating switch 120-1. The tray portion 204-5 (FIG. 28) whichaccommodates the dimmer cover assembly 206, also includes lightisolation openings 204-6 for the light pipe element 206-1 (FIG. 28).

In reference to FIGS. 30-31, detailed isometric views of the dimmeractuator cover 206 depicted in FIG. 20 are disclosed. FIG. 30 shows theunderside of the dimmer cover 206. An alignment mask 206-2 is disposedovertop the light pipe structure 206-1 to prevent undesired lightleakage from the light pipe. The down button light pipe 206-5, the upbutton light pipe 206-6, and the LED bar graph light pipes 206-7 areshown extending through the mask portion 206-2. In FIG. 31, the maskportion 206-2 is removed such that the light pipe structure 206-1 can beclearly seen within the dimmer cover 206.

Referring to FIG. 32, a cross-sectional view of the power control device10 depicted in FIG. 20 is disclosed. This view shows the aesthetic cover204 disposed over the functional switch 204-2 and other elementsunderneath, such as the logic PCB 10-2, separator 202-2 and the powerhandling PCB 10-1. Aesthetic cover 204 is configured to be removable bythe user as is dimmer cover 206.

While several inventive embodiments have been described and illustratedherein, those of ordinary skill in the art will readily envision avariety of other means and/or structures for performing the functionand/or obtaining the results and/or one or more of the advantagesdescribed herein, and each of such variations and/or modifications isdeemed to be within the scope of the inventive embodiments describedherein. More generally, those skilled in the art will readily appreciatethat all parameters, dimensions, materials, and configurations describedherein are meant to be exemplary and that the actual parameters,dimensions, materials, and/or configurations will depend upon thespecific application or applications for which the inventive teachingsis/are used. Those skilled in the art will recognize, or be able toascertain using no more than routine experimentation, many equivalentsto the specific inventive embodiments described herein. There is nointention to limit the invention to the specific form or formsdisclosed, but on the contrary, the intention is to cover allmodifications, alternative constructions, and equivalents falling withinthe spirit and scope of the invention, as defined in the appendedclaims. It is, therefore, to be understood that the foregoingembodiments are presented by way of example only and that, within thescope of the appended claims and equivalents thereto; inventiveembodiments may be practiced otherwise than as specifically describedand claimed.

All references, including publications, patent applications, andpatents, cited herein are hereby incorporated by reference to the sameextent as if each reference were individually and specifically indicatedto be incorporated by reference and were set forth in its entiretyherein.

All definitions, as defined and used herein, should be understood tocontrol over dictionary definitions, definitions in documentsincorporated by reference, and/or ordinary meanings of the definedterms.

The use of the terms “a” and “an” and “the” and similar referents in thecontext of describing the invention (especially in the context of thefollowing claims) are to be construed to cover both the singular and theplural, unless otherwise indicated herein or clearly contradicted bycontext.

As used herein in the specification and in the claims, the phrase “atleast one,” in reference to a list of one or more elements, should beunderstood to mean at least one element selected from any one or more ofthe elements in the list of elements, but not necessarily including atleast one of each and every element specifically listed within the listof elements and not excluding any combinations of elements in the listof elements. This definition also allows that elements may optionally bepresent other than the elements specifically identified within the listof elements to which the phrase “at least one” refers, whether relatedor unrelated to those elements specifically identified. Thus, as anon-limiting example, “at least one of A and B” (or, equivalently, “atleast one of A or B,” or, equivalently “at least one of A and/or B”) canrefer, in one embodiment, to at least one, optionally including morethan one, A, with no B present (and optionally including elements otherthan B); in another embodiment, to at least one, optionally includingmore than one, B, with no A present (and optionally including elementsother than A); in yet another embodiment, to at least one, optionallyincluding more than one, A, and at least one, optionally including morethan one, B (and optionally including other elements); etc.

It should also be understood that, unless clearly indicated to thecontrary, in any methods claimed herein that include more than one stepor act, the order of the steps or acts of the method is not necessarilylimited to the order in which the steps or acts of the method arerecited.

Approximating language, as used herein throughout the specification andclaims, may be applied to modify any quantitative representation thatcould permissibly vary without resulting in a change in the basicfunction to which it is related. Accordingly, a value modified by a termor terms, such as “about” and “substantially”, are not to be limited tothe precise value specified. In at least some instances, theapproximating language may correspond to the precision of an instrumentfor measuring the value. Here and throughout the specification andclaims, range limitations may be combined and/or interchanged; suchranges are identified and include all the sub-ranges contained thereinunless context or language indicates otherwise.

The recitation of ranges of values herein are merely intended to serveas a shorthand method of referring individually to each separate valuefalling within the range, unless otherwise indicated herein, and eachseparate value is incorporated into the specification as if it wereindividually recited herein.

All methods described herein can be performed in any suitable orderunless otherwise indicated herein or otherwise clearly contradicted bycontext. The use of any and all examples, or exemplary language (e.g.,“such as”) provided herein, is intended merely to better illuminateembodiments of the invention and does not impose a limitation on thescope of the invention unless otherwise claimed.

No language in the specification should be construed as indicating anynon-claimed element as essential to the practice of the invention.

In the claims, as well as in the specification above, all transitionalphrases such as “comprising,” “including,” “carrying,” “having,”“containing,” “involving,” “holding,” “composed of,” and the like are tobe understood to be open-ended, i.e., to mean including but not limitedto. Only the transitional phrases “consisting of” and “consistingessentially of” shall be closed or semi-closed transitional phrases,respectively, as set forth in the United States Patent Office Manual ofPatent Examining Procedures, Section 2111.03.

What is claimed:
 1. An electrical wiring device comprising: a housingassembly including a plurality of terminals at least partially disposedtherein, the plurality of terminals being configured to be coupled to anAC power source and at least one electrical load; a sensor elementcoupled to the plurality of terminals and configured to provide a sensorsignal based on at least one load power parameter of the at least oneelectrical load; at least one variable control mechanism coupled to thehousing assembly, the at least one variable control mechanism beingconfigured to adjustably select a user adjustable load setting, the useradjustable load setting being adjustable between a minimum setting and amaximum setting; at least one series pass element coupled between the ACpower source and at least one electrical load, the at least one seriespass element being configured to provide output power to the at leastone electrical load in accordance with the user load setting, the outputpower being less than or equal to the AC power; and a regulation circuitcoupled to the sensor element and the at least one series pass element,the regulation circuit being configured to enter a calibration mode whenAC power is applied to at least a portion of the plurality of terminals,in the calibration mode the regulation circuit being configured toprovide the at least one series pass element with an initial outputpower setting while monitoring the at least one load power parameter,the regulation circuit being further configured to increment the initialoutput power setting to at least one incremental output power settingwhile monitoring the at least one load power parameter, the regulationcircuit being configured to identify a load type of the at least oneelectrical load based on the at least one incremental output powersetting and the at least one load power parameter that results in the atleast one electrical load being energized, the regulation circuitselecting calibration values based on the load type, the selectedcalibration values corresponding to the minimum setting and the maximumsetting.
 2. The device of claim 1, wherein the plurality of terminalsincludes a neutral terminal or a ground terminal.
 3. The device of claim1, wherein the identified load type determines if the at least oneelectrical load operates in a forward phase control mode or a reversephase control mode.
 4. The device of claim 1, wherein the regulationcircuit includes a microcontroller coupled to a memory, the memory beingconfigured to store a plurality of characteristic load curves storedtherein, the plurality of characteristic load curves including aplurality of incremental power settings and a plurality of load powerparameters, each characteristic load curve of the plurality ofcharacteristic load curves correlating each load type with apredetermined incremental output power setting versus a predeterminedload power parameter.
 5. The device of claim 4, wherein thepredetermined load power parameter includes an inrush current parameter.6. The device of claim 1, further comprising a power supply coupled tothe AC power source, the power supply being configured to provide atleast one supply voltage.
 7. The device of claim 6, wherein the powersupply is a half wave power supply that is selectively coupled to the ACpower source via one of three diodes, and wherein the plurality ofterminals includes a phase terminal, a first traveler terminal and asecond traveler terminal, the power supply being individually coupled tophase terminal, a first traveler terminal and a second traveler terminalby corresponding diodes of the three diodes.
 8. The device of claim 1,wherein the regulation circuit includes a zero cross circuit coupled tothe AC power source via one of three electrical paths, each of the threeelectrical paths including a diode.
 9. The device of claim 8, whereineach of the three electrical paths are coupled to one of a firsttraveler terminal, a second traveler terminal or a phase terminal. 10.The device of claim 1, wherein the regulation circuit is configured toenter the calibration mode when at least a portion of the at least onevariable control mechanism is actuated.
 11. The device of claim 10,wherein the portion includes an ON/OFF control.
 12. The device of claim1, wherein the sensor element is a current sensor configured to sensecurrent propagating through the at least one electrical load.
 13. Thedevice of claim 1, wherein the at least one electrical load is selectedfrom a group of electrical loads including a variable speed motor, anincandescent lighting load, a magnetic low voltage (MLV) load, afluorescent lighting load, an electronic ballast (EFL) type lightingload, a halogen light load, an electronic low voltage (ELV) load, and acompact florescent light (CFL) load.
 14. The device of claim 1, whereinthe series pass element is selected from a group of series pass elementsincluding a thyristor device, a triac device, and at least onetransistor device.
 15. The device of claim 14, wherein the at least onetransistor device includes a first MOSFET transistor coupled to a secondMOSFET transistor, the first MOSFET transistor being configured toprovide the output power in a first half cycle of the AC power sourceand the second MOSFET transistor being configured to provide the outputpower in a second half cycle of the AC power source.
 16. An electricalwiring device comprising: a housing assembly including a plurality ofterminals at least partially disposed therein, the plurality ofterminals being configured to be coupled to an AC power source and atleast one electrical load; a sensor element coupled to the plurality ofterminals and configured to provide a sensor signal based on at leastone load power parameter of the at least one electrical load; at leastone variable control mechanism coupled to the housing assembly, the atleast one variable control mechanism being configured to adjustablyselect a user adjustable load setting, the user adjustable load settingbeing adjustable between a minimum setting and a maximum setting; atleast one series pass element coupled between the AC power source and atleast one electrical load, the at least one series pass element beingconfigured to provide output power to the at least one electrical loadin accordance with the user load setting, the output power being lessthan or equal to the AC power; and a regulation circuit coupled to thesensor element and the at least one series pass element, the regulationcircuit being configured to enter a calibration mode when AC power isapplied to at least a portion of the plurality of terminals, in thecalibration mode the regulation circuit being configured to provide theat least one series pass element with an initial output power settingwhile monitoring the at least one load power parameter, the regulationcircuit being further configured to increment the initial output powersetting to at least one incremental output power setting whilemonitoring the at least one load power parameter, the regulation circuitbeing configured to select a forward phase control mode or a reversephase control mode based on the at least one incremental output powersetting or the at least one load power parameter that results in the atleast one electrical load being energized.
 17. The device of claim 16,wherein the regulation circuit selects calibration values based on whichof the forward phase control mode or the reverse phase control mode isselected, the selected calibration values corresponding to the minimumsetting and the maximum setting.
 18. The device of claim 16, wherein theregulation circuit is configured to identify a load type of the at leastone electrical load based on the at least one incremental output powersetting and the at least one load power parameter that results in the atleast one electrical load being energized, the regulation circuitselecting calibration values based on the load type, the selectedcalibration values corresponding to the minimum setting and the maximumsetting.
 19. The device of claim 16, wherein the plurality of terminalsincludes a neutral terminal or a ground terminal.
 20. The device ofclaim 16, wherein the regulation circuit includes a microcontrollercoupled to a memory, the memory being configured to store a plurality ofcharacteristic load curves stored therein, the plurality ofcharacteristic load curves including a plurality of incremental powersettings and a plurality of load power parameters, each characteristicload curve of the plurality of characteristic load curves correlatingeach load type with a predetermined incremental output power settingversus a predetermined load power parameter.
 21. The device of claim 16,further comprising a power supply coupled to the AC power source, thepower supply being configured to provide at least one supply voltage.22. The device of claim 21, wherein the power supply is a half wavepower supply that is selectively coupled to the AC power source via oneof three diodes, and wherein the plurality of terminals includes a phaseterminal, a first traveler terminal and a second traveler terminal, thepower supply being individually coupled to phase terminal, a firsttraveler terminal and a second traveler terminal by corresponding diodesof the three diodes.
 23. The device of claim 16, wherein the regulationcircuit includes a zero cross circuit coupled to the AC power source viaone of three electrical paths, each of the three electrical paths areselectively coupled to one of a first traveler terminal, a secondtraveler terminal or a phase terminal via a diode.
 24. The device ofclaim 16, wherein the regulation circuit is configured to enter thecalibration mode when at least a portion of the at least one variablecontrol mechanism is actuated, the portion including an ON/OFF control.25. The device of claim 16, wherein the sensor element is a currentsensor configured to sense current propagating through the at least oneelectrical load.
 26. The device of claim 16, wherein the at least oneelectrical load is selected from a group of electrical loads including avariable speed motor, an incandescent lighting load, a magnetic lowvoltage (MLV) load, a fluorescent lighting load, an electronic ballast(EFL) type lighting load, a halogen light load, an electronic lowvoltage (ELV) load, and a compact florescent light (CFL) load.
 27. Thedevice of claim 16, wherein at least one load power parameter is basedon a current propagating through the at least one electrical load. 28.The device of claim 16, wherein the series pass element is selected froma group of series pass elements including a thyristor device, a triacdevice, and at least one transistor device.
 29. The device of claim 28,wherein the at least one transistor device includes a first MOSFETtransistor coupled to a second MOSFET transistor, the first MOSFETtransistor being configured to provide the output power in a first halfcycle of the AC power source and the second MOSFET transistor beingconfigured to provide the output power in a second half cycle of the ACpower source.
 30. A method for controlling an electrical wiring device,the method comprising: providing a housing assembly having a pluralityof terminals at least partially disposed therein, the plurality ofterminals being configured to be coupled to an AC power source and atleast one electrical load, the housing also including at least onevariable control mechanism coupled to the housing assembly, the at leastone variable control mechanism being configured to adjustably select auser adjustable load setting, the user adjustable load setting beingadjustable between a minimum setting and a maximum setting, the housingfurther including at least one series pass element coupled between theAC power source and at least one electrical load, the at least oneseries pass element being configured to provide output power to the atleast one electrical load in accordance with the user load setting, theoutput power being less than or equal to the AC power; entering acalibration mode when AC power is applied to at least a portion of theplurality of terminals; providing the at least one series pass elementwith an initial output power setting while monitoring at least one loadpower parameter; incrementing the initial output power setting to atleast one incremental output power setting while monitoring the at leastone load power parameter; and selecting a forward phase control mode ora reverse phase control mode based on the at least one incrementaloutput power setting or the at least one load power parameter thatresults in the at least one electrical load being energized.
 31. Themethod of claim 30, further comprising the step of selecting thecalibration values based on which of the forward phase control mode orthe reverse phase control mode is selected, the selected calibrationvalues corresponding to the minimum setting and the maximum setting. 32.The method of claim 30, further comprising the step of identifying aload type of the at least one electrical load based on the at least oneincremental output power setting and the at least one load powerparameter that results in the at least one electrical load beingenergized.
 33. The method of claim 30, further comprising the step ofselecting calibration values based on the load type, the selectedcalibration values corresponding to the minimum setting and the maximumsetting.
 34. The method of claim 30, wherein the plurality of terminalsincludes a neutral terminal or a ground terminal.
 35. The method ofclaim 30, wherein the step of providing includes providing amicrocontroller coupled to a memory, the memory being configured tostore a plurality of characteristic load curves stored therein, theplurality of characteristic load curves including a plurality ofincremental power settings and a plurality of load power parameters,each characteristic load curve of the plurality of characteristic loadcurves correlating each load type with a predetermined incrementaloutput power setting versus a predetermined load power parameter. 36.The method of claim 30, wherein the step of providing includes providinga power supply coupled to the AC power source, the power supply beingconfigured to provide at least one supply voltage.
 37. The method ofclaim 36, wherein the power supply is a half wave power supply that isselectively coupled to the AC power source via one of three diodes, andwherein the plurality of terminals includes a phase terminal, a firsttraveler terminal and a second traveler terminal, the power supply beingindividually coupled to phase terminal, a first traveler terminal and asecond traveler terminal by corresponding diodes of the three diodes.38. The method of claim 30, wherein the step of providing includesproviding a zero cross circuit coupled to the AC power source via one ofthree electrical paths, each of the three electrical paths areselectively coupled to one of a first traveler terminal, a secondtraveler terminal or a phase terminal via a diode.
 39. The method ofclaim 30, further comprising the step of entering a calibration modewhen at least a portion of the at least one variable control mechanismis actuated, the portion including an ON/OFF control.
 40. The method ofclaim 30, wherein the series pass element is selected from a group ofseries pass elements including a thyristor device, a triac device, andat least one transistor device.
 41. The method of claim 40, wherein theat least one transistor device includes a first MOSFET transistorcoupled to a second MOSFET transistor, the first MOSFET transistor beingconfigured to provide the output power in a first half cycle of the ACpower source and the second MOSFET transistor being configured toprovide the output power in a second half cycle of the AC power source.